1. Field of the Invention
The present invention relates to an ultraviolet-hardenable adhesive for bonding a water-swellable, ophthalmic-lens blank to a support member in producing a water-swellable ophthalmic lens such as a contact lens and an intraocular lens, a method of bonding a water-swellable ophthalmic-lens blank to a support member with an adhesive, and a process of producing a water-swellable ophthalmic lens using an adhesive.
2. Discussion of the Prior Art
Various adhesives are available for industrial and domestic uses. In particular, when an ophthalmic-lens blank is subjected to workings, such as machining and polishing, and/or necessary treatments in producing an ophthalmic lens such as a contact lens and an intraocular lens, an adhesive is used to bond the lens blank to a support member. Since the worked lens must be separated from the support member, it is required to use an adhesive which permits the lens to easily be separated from the support member.
U.S. Pat. No. 4,619,082 (Dent et al.), teaches use of a molten wax for bonding a lens blank to a support member. Molten wax normally melts at 60 to 70.degree. C., and the wax in molten state is used as an adhesive. Therefore, if it takes a comparatively long time to finish the step of bonding the lens block to the support member, the wax is hardened during the step, whereby the lens blank may not accurately be positioned relative to the support member.
Further, it has been proposed to use other sorts of adhesives, for example a room temperature-hardenable adhesive, a cyanoacrylate-type adhesive ("instant adhesive") and a two-part adhesive. The room temperature-hardenable adhesive has the same problem as the above-indicated molten wax, because this adhesive is hardened due to moisture in ambient air, which acts as a catalyst. Specifically, if a comparatively long time is taken to finish the bonding step, the adhesive is hardened during the step. Thus, the adhesive is of low controllability in use thereof and is not suitable for this purpose. In the case of the cyanoacrylate-type adhesive, a lens blank is instantly secured to a support member due to the specific nature of the adhesive, therefore the lens blank may not accurately be positioned relative to the support member. After having been subjected to the workings and/or treatments, the produced lens may not easily be separated from the support member. Furthermore, the two-part adhesive has the problem of low controllability in use for bonding a lens blank to a support member, because the adhesive is hardened upon mixture of the two parts or fluids.
In particular, the conventional adhesives are not suitable for bonding a water-absorbable or water-swellable, ophthalmic-lens blank to a support member, due to high affinity of the adhesives to the material of the lens blank. Specifically, the conventional adhesives have the problem of penetrating into the lens blank and thereby damaging the shaped optical surface of the lens blank.